Hydraulic press

ABSTRACT

In an hydraulic press for forming sheet material which includes a press stand with a recess therein and an expansible pressure bag and a pad of elastic material within the recess, and which has an operating space below the recess into which a trough-shaped support member for tools and workpieces can be inserted, metallic strip seals are provided which overlie the edges of the pad and extend over the wall portions at either end of the recesses. Such wall portions are provided with grooves, into which flanges on the outer ends of the strip seals engage. The strip seals are supported by hat-shaped elements arranged in recesses in such wall portions which are secured to the strip seals and are held in position by coil springs engaging bolts secured in the recesses.

United States Patent Hellgren Apr. 8, 1975 [S ll HYDRAULKC PRESS3.545.3-ll l2/l97U Grunkowski et all 72/63 [75] lmcmor' gigg fi Hellgren\HMLMS Primary E.i'umiizer-Richard .l. Herhst (73] Assignee: AllmannaSvenska Elektriska 57 ABSTRACT Akuebolage imam Sweden ln Llll hydraulicpress for forming sheet material which [22} Filed: Oct. I8. 1973includes a press stand with a recess therein and an ex unsihle ressurehti and u ad of elastic material [2]] App! 407506 iiithin this recess.an?! which has lln operating space below the recess into which ittrough-shaped support [30] Foreign Application Priority Data member fortools and workpieces can be inserted. me-

[4 1973 Sweden 4747/73 ttillic strip seals are provided which overliethe edges of the pad and extend over the wall portions at either 52 s CLI I V I g I l I I r 4 t v 72 3 end of the recesses. Such wall portionsare provided 5 H h. C] H. N n 22/12 with grooves. into which flanges onthe outer ends of [58] Field of Search 72/63; 100/21 1 the Strip W18engage The strip M15 m pp y hat-shaped elements arranged in recesses insuch wall [56] References Cited portions which are secured to the stripseals and are UNITED STATES PATENTS held in position by coil springsengaging bolts secured r in the recesses. 1696.184 12/1954 Demurest72163 177L850 Il/I956 Whcelon 4. 72/63 4 Claims. 6 Drawing FiguresPATENTEDAPR 8|H75 $875,778

22 2 2/b 2/0 38 40 2/ 2/c 200 2/d 42 25 Fig. 5

22 2 21b 21a 38 40 2/ 2/c 20o 2/d 42 25 Fig.6

booooo oooo HYDRAULIC PRESS BACKGROUND OF THE INVENTION l. Field of theInvention The present invention relates to a press with a very largeworking area for forming sheet-metal by means of a diaphragm which ispressed against pieces of sheet metal resting on a forming block.Aircraft parts such as ribs and the like can be manufactured in such apress.

2. The Prior Art The press according to the invention comprises a pressstand having a window opening with substantially rectangularcross-section. A frame or plate is suspended in the press stand and insaid frame or plate a diaphragm is attached forming a pressure bag. Onthe underside of the diaphragm there is a thick layer of elasticmaterial which forms a pad forming workpieces. workpieces are placed atthe bottom of a troughshaped support member which is pushed into theoperating space below the plate with the pressure bag and pad. afterwhich the pressure bag is supplied with pressure medium. This will causethe pad to be pressed against one or more workpieces at the bottom ofthe trough-shaped support member.

There exist very great problems in such presses in preventing the padfrom being pressed out through gaps between the support member and thesurrounding construction elements in presses. Particularly great are theproblems of preventing the pad from being pressed out through the gapbetween the upper surface of the support member and the support plate ofthe pressure bag at the end openings of the press.

In known constructions an L-shaped strip is used which is attached in aresilient manner in the past of the support plate of the pressure bagwhich forms the end wall in the space where the pressure bag and its padare arranged. One flange of the L-shaped strip is directly attached bybolts in the end wall of the support plate and the elasticity isobtained by bending the flange. By providing notches in the flange anincrease in the length of the spring is achieved. The forces whichaffect the strip in the pressing are great and sometimes cause theattachment bolts to burst after only a short time. It has also beendifficult to make the resilient parts of the strip flange sufficientlyrigid. These bolt and strip ruptures have caused prolonged shut-downs.

SUMMARY OF THE INVENTION According to the invention the strip isconstructed and arranged in such a way that all forces affecting thestrip in the axial directions of the press are transmitted to the wallwhich defines the space of the pressure bag, and the resilientattachment of the strip is such that the attachment bolts are onlysubjected to tensile forces. The strip seal is made with a U-shapedportion with a flange projecting into a slot in said wall.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described moreclosely with reference to the accompanying drawings.

FIG. 1 shows a side view of a press plant;

FIG. 2 shows a section on the line AA of FIG. I;

FIG. 3 is a vertical longitudinal section on the line 3-8 of FIG. 2;

FIG. 4 shows on a larger scale a section through the strip seal andadjacent parts on the same line BB; and

FIGS. 5 and 6 show the position of the strip sea] at two moments duringa press operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings. I designates apress and 2 a trough shaped support member on which workpieces can beplaced. The support member is provided with transport rolls 3 running ontracks 4. The support member is displaceable between the position shownin FIG. I, where pressed sheet-metal pieces are removed and new piecesare put on forms, and a position pushed into the press where the presspad forms the sheet-metal pieces. The press shown is of the kind havinga press stand which is constructed of an upper yoke I0, a lower yoke IIand two intermediate spaces 12 which are kept together by a pre-stressedstrip sheath I3. This sheath is surrounded by a protective plate 14.

The press rests on a support I5 having bearing plate beds adjusted tothe press. The yokes and spaces form a rectangular window opening in thepress. In the space within the press a plate 16 is mounted in the yoke10 by means of bolts now shown. In a recess in said plate a diaphragm I7is attached with the help of the plate 18 and the bolts I9 so that apressure bag is formed. The space between the diaphragm I7 and the plateI8 communicates with a pressure source (not shown] through pipes 29 byway of valves and pipes (not shown). The diaphragm is connected to athick pad 20 of elastic material. Adjacent the recess where thediaphragm and pad are arranged there is a support strip 2I which isintended to prevent the pad 20 from being pressed out through the gap 22between the plate I6 and the upper surface of the trough-shaped supportmember 2 during a press operation when the pad is pressed against theplate 23 on the forming block 24 in the recess 25 in the support member2 by the press me dium in the pressure bag formed of the diaphragm I7and the plate 18.

The wheels 3 of the support member 2 are mounted on axle pins 26 betweenthe brackets 27. In the tracks 4 nearest the press there are plates 31supported by springs 30, said plates having a lifting force somewhatexceeding the weight of the support member 2 with the forming block 24and the workpiece 23. In this way these plates yield downwardly when thepad 20 exerts a downward force against the workpiece 23 on the formingblock 24 resting on the bottom 32 of the recess 25. The support member 2will then rest against the yoke 11, which will thus take up the mainpart of the downward force.

The strip seal 21, a part of which overlaps the edge of the pad 20, isE-shaped and is provided with a web 210, a flange 21b. a flange 21c anda flange 21d. The pad 20 has a shape adapted to the shape of the stripseal 21, with a part 200 projecting between the flanges 21c and 21d. Inthe outer wall 16a of the plate 16, that is, the wall portion at the endof the recess. there is a slot 35. The flange 21b projects into thisslotv The flange 21c rests against the vertical. inner surface 36 of thewall 16a. In the wall there are bores 37. Through an aperture 38 in theweb 21a. a hat-shaped sleeve 39 projects into the bore 37. The stripseal 21 is suspended from the wall 16a with the help of a bolt 40 and apres sure spring 41 and said sleeve 39. When pushing in and pulling outthe trough-shaped support member 2, the pad 20 and the strip are in theposition shown in FIGS.

3 and 4. When pressure medium is supplied to the pres sure bag thediaphragm l7 and the pad are first stretched and the pad tends to pullthe strips seal 2] in wards [see FIG. 5) The resulting tensile force aretransmitted by way of the flange Zlb and the wall of the slot to thewall 161:. When the pad is pressed against the support member 2 it willsimultaneously be pressed against the strip seal 2] and the wall 36. Thestrip seal 2] will then be pressed against the surface 42 of the supportmember. that is. the wall portion at the end of the trough as well asthe wall 36 and will therefore bridge over the gap 22. thus preventingthe pad from being pressed out through the gap and being destroyed Bymeans of the present invention all the forces in the horizontaldirection which act on the strip seal are directly transmitted to thewall 16a from the flanges 22c and 21b. respectively. The attachmentbolts 40 will then only absorb tensile forces These are limited to avalue determined by the springs 41. The whole strip 21 will rest on thesupport member 2, so the web Zlu will not be subjected to considerablefexural stresses as has been the case in previous press constructions, Asatis factory length of service can be obtained despite the use of moresimple construction of the strip seal I claim:

1. Hydraulic press for forming sheet material comprising a press standincluding a first part having a re cess therein and having walls at eachend of the recess with transverse faces an expansible pressure bag and apad of elastic material within the recess. said press stand including asecond part opposite the first part and spaced therefrom to provide anoperating space extending through the press stand having end openings, asupport member for tools and workpieces insertable into said operatingspace having transverse faces opposable to the transverse faces of thefirst part, grooves in said transverse faces substantially parallel tothe plane of the end openings, metalli strip seals adjacent the endopenings of the operating space overlying the edges of the pad endhaving flanges engaging in the grooves and having portions between thetransverse faces of the first part and the transverse faces of thesuport member, said portions overlying the transverse faces of thesupport part and means mounting the strip seals on the first part 2.Press as claimed in claim I, in which the mounting means mount the stripseals for movement towards and away from the transverse faces of thefirst part.

3. Press as claimed in claim 1. in which the mounting means mount thestrip seals for movement towards and away from the transverse faces ofthe first part. the mounting means being resilient and resistingmovement of the strip seals away from the transverse faces of thesupport part,

4. Press as claimed in claim 3, in which the transverse faces of thefirst part have notches therein and the mounting means compriseshatshaped sleeves which are attached by their lower parts in the stripseals and which project into said notches, pressure springs in saidsleeves and bolts attached in the transverse faces engaging saidsprings.

1. Hydraulic press for forming sheet material comprising a press standincluding a first part having a recess therein and having walls at eachend of the recess with transverse faces, an expansible pressure bag anda pad of elastic material within the recess, said press stand includinga second part opposite the first part and spaced therefrom to provide anoperating space extending through the press stand having end openings, asupport member for tools and workpieces insertable into said operatingspace having transverse faces opposable to the transverse faces of thefirst part, grooves in said transverse faces substantially parallel tothe plane of the end openings, metalli strip seals adjacent the endopening of the operating space overlying the edges of the pad end havingflanges engaging in the grooves and having portions between thetransverse faces of the first part and the transverse faces of thesuport member, said portions overlying the transverse faces of thesupport part and means mounting the strip seals on the first part. 2.Press as claimed in claim 1, in which the mounting means mount the stripseals for movement towards and away from the transverse faces of thefirst part.
 3. Press as claimed in claim 1, in which the mounting meansmount the strip seals for movement towards and away from the transversefaces of the first part, the mounting means being resilient andresisting movement of the strip seals away from the transverse faces ofthe support part.
 4. Press as claimed in claim 3, in which thetransverse faces of the first part have notches therein and the mountingmeans comprises hat-shaped sleeves which are attached by their lowerparts in the strip seals and which project into said notches, pressuresprings in said sleeves and bolts attached in the transverse facesengaging said springs.